A Black Hawk helicopter on loan from the Army National Guard made three trips in and out of the Boulder County foothills Tuesday, hauling dug-up marijuana plants and equipment away from what officials say was an illegal grow operation discovered last week.

In total, Cmdr. Scott Williams of the Boulder County Drug Task Force estimated the law enforcement team that broke up the clandestine operation confiscated between 300 and 400 juvenile marijuana plants worth at least $100,000.

The investigation into who is behind the grow, nestled among the pine trees on private land in the South St. Vrain Canyon, is ongoing, Williams said.

"I would say that these were experienced people that knew what they were doing, and I believe they may have been the same people who were here before," Williams said, referencing a larger-scale operation that law enforcement officials discovered on the opposite side of the same canyon in 2011.

"We think it is some kind of drug trafficking organization," he said. "We don't know if it is an organization out of Mexico, but we don't believe it is a local organization."

Boulder County officials were alerted Aug. 26 after hikers stumbled across the pot farm, said Cmdr. Heidi Prentup of the Sheriff's Office.

On Thursday, crews from the drug task force, Boulder County SWAT Team and Boulder County Fire Management Crew pulled the plants out of the ground and prepared them for Tuesday's airlift.

The Black Hawk helicopter, provided to Boulder County free of charge through the National Guard's drug task force, hauled an estimated 2,000 pounds of plants, chicken wire and equipment used to irrigate the roughly 1-acre marijuana farm down to an area near Longmont's Vance Brand Airport. Once on the ground, the material was loaded into a truck so that it could be hauled away and destroyed.

"This terrain was very difficult. There was a lot of rock — a lot of loose rock — and a lot of moist soil," Williams said, estimating the slope of the land was greater than a 45-degree angle. "It was basically in a natural ravine where you would have a natural water flow from the mountain."

Williams said the plants on the site were situated in groups of two or three packed in closely to trees, making the operation extremely hard to see from the air.

Logs, tarps, chicken wire and other materials had been used to establish a series of small dams down the ravine that collected rain water that was then transported via an irrigation system to the plants, he said.

The crop was made up of 3-foot tall plants that were still two to four weeks away from producing valuable marijuana buds, according to Williams.

The owners of the land do not live there and had no idea the farm was there, he said.

Williams said crews also found a campsite with food hung from trees in the area, and investigators are hopeful some of the material they collected there will help lead them to suspects.

If apprehended, the marijuana growers could face charges including felony drug distribution and drug cultivation, trespassing and other charges related to interfering with water rights.

Asked why people might undertake an illegal outdoor operation in a state where small-scale marijuana cultivation is legal for people ages 21 and up, Williams said, "profit."

"They know that they can take this marijuana and sell it," he said. "There are still 48 other states in the United States where marijuana isn't legal."